This application is based upon and claims the benefit of priority from Japanese Patent Application Number 2000-113578, filed Apr. 14, 2000, the entire contents of which are hereby incorporated by reference.
This invention relates to a bill validator for use in a vending machine or the like and, in particular, to an optical detecting section of the bill validator.
For example, a related bill validator has a structure illustrated in FIG. 1. In the bill validator 100, a paper currency bill or bank note 101 is inserted through a bill inlet 102 and sent to an insertion detecting section 105 comprising a light emitting element 103 and a light receiving element 104 and arranged behind the bill inlet 102. The light emitting element 103 is energized by an emission power supply 106 and emits a light beam towards the light receiving element 104. The light receiving element 104 receives the light beam after it is attenuated in luminous energy through the bill 101. Thus, the insertion of the bill 101 is detected by the light receiving element 104 as the attenuation in luminous energy. When the insertion of the bill 101 is detected, a controller 107 delivers a forward operation signal to a reversible driver 109 to rotate a transfer motor 108 in a forward direction so that the bill 101 is transferred inward, i.e., in a bill accepting direction by a transfer belt 110. When a forward end of the bill 101 reaches a magnetic head 111 and an optical validating sensor 114 comprising a light emitting element 112 and a light receiving element 113, detection signals are produced by the magnetic head 111 and the light receiving element 113 of the optical validating sensor 114. The detection signals are supplied to an amplifier circuit 115 to be amplified into amplified detection signals. The amplifier circuit 115 delivers the amplified detection signals to an A/D converter 116. The A/D converter 116 converts the amplified detection signals into digital detection signals and supplies the digital detection signals to a validating unit 117. The validating unit 117 starts acquisition of bill data given by the digital detection signals. The acquisition of the bill data is continuously carried out until a rear end of the bill 101 is transferred to a position right under the light receiving element 117 of the optical validating sensor 114. After the acquisition of the bill data is completed, the validating unit 117 judges whether the bill 101 is valid or invalid. In addition, the validating unit 117 calculates an average of luminous energy transmitted through the bill 101 and received by the light receiving element 113. If the average of luminous energy is smaller than a predetermined reference level, the validating unit 117 judges xe2x80x9coverlappedxe2x80x9d, i.e., the state in which two bills being overlapped are inserted.
If the validating unit 117 judges xe2x80x9cinvalidxe2x80x9d or xe2x80x9coverlappedxe2x80x9d, the controller 107 delivers a reverse operation signal to the reversible driver 109 to rotate the transfer motor 108 in a reverse direction so that the bill 101 is transferred outward, i.e., in a bill dispensing direction by the transfer belt 110. The transfer motor 108 continues the reverse rotation until the bill 101 escapes from the insertion detecting section 105 or until a time out occurs.
If the validating unit 117 judges xe2x80x9cvalidxe2x80x9d, the controller 107 delivers a valid bill signal to an external apparatus (not shown) and waits a storage request signal or a return request signal from the external apparatus.
The above-mentioned bill validator 100 is disadvantageous in the following respects. As described above, if the validating unit 117 judges xe2x80x9cinvalidxe2x80x9d or xe2x80x9coverlappedxe2x80x9d, the controller 107 delivers the reverse operation signal to the reversible driver 109 to rotate the transfer motor 108 in the reverse direction so that the bill 101 is transferred by the transfer belt 110 in the bill dispensing direction. However, since the judgment of xe2x80x9coverlappedxe2x80x9d is made at a later stage after the rear end of the bill 101 reaches the optical validating sensor 114, the bill 101 tends to be jammed in a transfer path. The transfer motor 108 continues the reverse rotation until the bill 101 escapes from the insertion detecting section 105 or until the time out occurs. If the bill 101 is removed from the bill validator 100 at a later time instant, the transfer motor 108 is excessively rotated. In this state, the bill 101 may be returned to a position beyond a clamping force between the transfer belt 110 and the guide roller 118 to be released and fallen out from the bill validator 100.
Upon judgment of xe2x80x9coverlappedxe2x80x9d, use is made of the reference level which is preliminarily determined at an appropriate value in an initial condition of the bill validator 100. If the optical validating sensor 114 as an optical section is deteriorated, comparison with the predetermined reference level becomes difficult. This inhibits a proper operation of the bill validator 100.
It is therefore an object of this invention to provide a bill validator capable of reliably judging xe2x80x9coverlappedxe2x80x9d in an early stage to prevent a bill from jamming and from being released and fallen out from the bill validator if the bill is transferred in a dispensing direction.
It is another object of this invention to provide a bill validator capable of readily updating a reference level for use in judgment of xe2x80x9coverlappedxe2x80x9d to an optimum value.
According to this invention, there is provided a bill validator comprising a bill inlet through which a bill is inserted, a transfer path arranged behind the inlet and connected to the inlet, a transferring mechanism for transferring the bill in the transfer path, a validating unit for validating the bill on a predetermined validating position of the transfer path, and an optical detecting section comprising a light emitting portion for emitting a light beam, a transmission light guide having a light input portion supplied with the flight beam from the light emitting portion and a light output portion for outputting the light beam inputted through the light input portion, and a light receiving portion for receiving the light beam from the light output portion, the light input and the light output portions of the transmission light guide being faced to the light emitting portion and the light receiving portion, respectively, with a first position of the transfer path interposed between the light input portion of the transmission light guide and the light emitting portion and with a second position of the transfer path interposed between the light output portion of the transmission light guide and the light receiving portion, the second position of the transfer path being different from the first position of the transfer path.